Just failed my first Fizz Buzz PHP assessment test..

So I just had a chance to take an online assessment test for a php developer job I applied for. I finished the php dev track here on treehouse and I know we just scratched the surface of object oriented programming, nonetheless I wasn't sure how to write out the answer for this can someone explain it to me? I believe I need to have the functions evaluate to be equal or not equal and generate fizz or buzz. Was I supposed to write an if statement or something similar?

Instructions: The aim of this test is to implement the FizzBuzz problem.

FizzBuzz is defined for the "natural numbers" (numbers greater than zero) as:

When divisible by 3, you should return "Fizz". When divisible by 5, you should return "Buzz". When divisible by both 3 and 5, you should return "FizzBuzz". When divisible by neither, you should return the number itself.

This is where I am supposed to put my solution

<?php        
class FizzBuzz {
    public function __construct($number) {
        $this->number = $number;
    }


    public function __toString() {
        return '1';

    }   


}


?>

<?php
require 'FizzBuzz.php';

class FizzBuzzTest extends PHPUnit_Framework_TestCase
{

    public function testInputOne()
    {
        $fizzbuzz = new FizzBuzz(1);
        $this->assertEquals('1', (string) $fizzbuzz);
    }

    public function testInputThree()
    {
        $fizzbuzz = new FizzBuzz(3);
        $this->assertEquals('Fizz', (string) $fizzbuzz);
    }

    public function testInputFive()
    {
        $fizzbuzz = new FizzBuzz(5);
        $this->assertEquals('Buzz', (string) $fizzbuzz);
    }

    public function testInputFifteen()
    {
        $fizzbuzz = new FizzBuzz(15);
        $this->assertEquals('FizzBuzz', (string) $fizzbuzz);
    }

    public function testInputOneHundredAndOne()
    {
        $fizzbuzz = new FizzBuzz(101);
        $this->assertEquals('101', (string) $fizzbuzz);
    }

    public function testInputNinetyNine()
    {
        $fizzbuzz = new FizzBuzz(99);
        $this->assertEquals('Fizz', (string) $fizzbuzz);
    }

    public function testInputOneHundred()
    {
        $fizzbuzz = new FizzBuzz(100);
        $this->assertEquals('Buzz', (string) $fizzbuzz);
    }

    public function testInputOneHundredAndFive()
    {
        $fizzbuzz = new FizzBuzz(105);
        $this->assertEquals('FizzBuzz', (string) $fizzbuzz);
    }

}
?>      

The console logs out 7 errors

PHPUnit 3.6.10 by Sebastian Bergmann.

.FFFFFFF

Time: 0 seconds, Memory: 1.75Mb

There were 7 failures:

1) FizzBuzzTest::testInputThree Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'Fizz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:16 /usr/local/bin/phpunit:46

2) FizzBuzzTest::testInputFive Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'Buzz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:22 /usr/local/bin/phpunit:46

3) FizzBuzzTest::testInputFifteen Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'FizzBuzz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:28 /usr/local/bin/phpunit:46

4) FizzBuzzTest::testInputOneHundredAndOne Failed asserting that '1' matches expected '101'.

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:34 /usr/local/bin/phpunit:46

5) FizzBuzzTest::testInputNinetyNine Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'Fizz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:40 /usr/local/bin/phpunit:46

6) FizzBuzzTest::testInputOneHundred Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'Buzz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:46 /usr/local/bin/phpunit:46

7) FizzBuzzTest::testInputOneHundredAndFive Failed asserting that two strings are equal. --- Expected +++ Actual @@ @@ -'FizzBuzz' +'1'

/tmp/sandbox-dde76935d8b8506f0c22a2927b5f978eaf9e42e4/FizzBuzzTest.php:52 /usr/local/bin/phpunit:46

FAILURES! Tests: 8, Assertions: 8, Failures: 7.